A MORPHOLOGICAL STUDY ON THE NEURAL TUBE DEFECTS INDUCED BY BIS-A-TDA / 解剖学报

ABSTRACT

30 sexually mature, virgin female SD rats, weighed 200-270 g were mated and used for the study of the teratogenic effect of N, N-methylene-bis (2-amino-1,3,4-thiadiazole) (Bis-A-TDA) on fetal neural tube formation and to explore the possible morphological mechanism of neural tube defects (NTD). In the morning of day 10 of gestation, the experimental group was administered with 10mg/kg body weight Bis-A-TDA mixed in peanut oil, and the control group with the same amount of peanut oil only. The results Showed that the incidence of NTD was 52.9% and the majority of NTD were excencephaly and encephalocele in the experimental group. In the early stage of NTD formation, some neuroepithelial cells showed vacuolated degeneration and necrosis, and the mitochondria became swollen and with indistinct or even disappeared crista. The intercellular spaces widened, and some cells escaped into the lumen of neural tube. The mitotic index of neuroepitbelial cells were sharply decreased. In the closure region of the telencephalon, similar changes of the neuroepithelium were present also, and decreased migration of mesodermal cells was noted. We consider the failure of cranial neural folds to approximate and closure was caused mainly by the damage of neuroepithelial cells, inhibition of cell proliferation, alteration of intercellular junctions and the changes of topographical arrangement of the neuroepithelium. The damage and delayed migration of mesodermal cells might also be involved in this event.